Please help me solve this four equations with methode newton-raphson urgent (i have MATLAB R2010a)

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yahia mehda 2016-5-7

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https://ww2.mathworks.cn/matlabcentral/answers/283029-please-help-me-solve-this-four-equations-with-methode-newton-raphson-urgent-i-have-matlab-r2010a

评论： Maneet Goyal 2016-5-12

hi ,i need file fonction and the code matlab to solve those 4 equations [cos(3.θ1)+cos(3.θ2)+cos(3.θ3)+cos(3.θ4) ]=0 ; [cos(5.θ1)+cos(5.θ2)+cos(5.θ3)+cos(5.θ4) ]=0 ; [cos(7.θ1)+cos(7.θ2)+cos(7.θ3)+cos(7.θ4) ]=0 ; [cos(9.θ1)+cos(9.θ2)+cos(9.θ3)+cos(9.θ4) ]=0 ; with first condition θ1=0.314 ; θ2=0.628 ; θ3=0.945 ; θ4=1.225 ; in interval [0 pi/2] ; the angel's with radiane not degrees thnx

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Jan 2016-5-7

@yahia mehda: Please read this thread: Answers: Why your question is not urgent . You will see, that trying to push the voluntary helpers reduce their motivation to post an answer.

The strange notation with "θ1" is simply confusing. Posting the values directly would be a much better idea when you want others to assist you.

The forum usually ignore people, how do not show any own effort. Together with the "urgent" and the annoying "plllz" the chances to get an answer are really small. So better edit the question and show whatyou have tried so far, even if it does not work.

yahia mehda 2016-5-7

thnx bro iam new here ill edit it thanx for the advice

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Answer 1

Maneet Goyal 2016-5-7

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https://ww2.mathworks.cn/matlabcentral/answers/283029-please-help-me-solve-this-four-equations-with-methode-newton-raphson-urgent-i-have-matlab-r2010a#answer_221207

在 MATLAB Online 中打开

Your problem requires the output to be in a certain range:

[0 2*pi]

I suggest using fmincon. However, the your equations can be put in a function as below:

function out = proby(theta)
out = zeros(4,1);
out(1) = cos(3*theta(1))+...);
out(2) = cos(5*theta(1))+...);
out(3) = cos(7*theta(1))+...);
out(4) = cos(9*theta(1))+...);
end

The fsolve command can be easily applied over such a function. Since you are new, try the following to learn about using fsolve.

help fsolve

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yahia mehda 2016-5-7

编辑：Walter Roberson 2016-5-7

在 MATLAB Online 中打开

function out = proby(theta)
out = zeros(4,1);
out(1) = cos(3*theta(1))+cos(3*theta(2))+cos(3*theta(3))+cos(3*theta(4));
out(2) = cos(5*theta(1))+cos(5*theta(2))+cos(5*theta(3))+cos(5*theta(4));
out(3) = cos(7*theta(1))+cos(7*theta(2))+cos(7*theta(3))+cos(7*theta(4));
out(4) = cos(9*theta(1))+cos(9*theta(2))+cos(9*theta(3))+cos(9*theta(4));
end

i didn't understand fsolve how it work

the result i want it :

i find theta 1 and theta 2 and theta 3 and tetha 4 In order to be four equations equal to zero

Maneet Goyal 2016-5-12